This invention deals with aqueous hair treating compositions utilizing adducts of (1) low molecular weight aminopolysaccharides derived from chitosan with (2) hydrolyzed keratin protein comprising mixtures of amino acids.
Many hair care products contain polymeric ingredients for the purpose of improving attributes such as set holding and the property perceived as "body". Unfortunately, these polymers may undesirably alter other attributes such as feel, sheen, or hair combing ease. This is due in part to the fact that many polymers produce fiber coatings which have surface friction and reflectance properties very different from clean, intact hair.
It is also known to use a wide variety of protein materials in the formulation of modern hair care products to provide good feel and combing properties. However, such materials have been found to be generally ineffective in increasing set holding to any great extent.
We have discovered a class of materials, which when formulated in conventional aqueous hair treating compositions such as shampoos and conditioning rinses, provides an unexpected combination of set holding and conditioning benefits. In addition, a smooth, soft feel is imparted to the hair and combing, both wet and dry, is markedly improved. Furthermore, the hair appears to have more body, exhibits improved luster, and, unexpectedly, provides improved set holding than is the case when either of the individual ingredients is employed alone.
These benefits are derived from the inclusion of certain adducts of (1) low molecular weight aminopolysaccharides derived from chitosan with (2) hydrolyzed keratin protein comprising mixtures of amino acids as will be hereinafter more fully described.
The exact nature of the mode of action of these adducts in enhancing set improvement and combing properties of treated hair is not known. It is known, however, that aminopolysaccharides are used in the food industry to precipitate proteinaceous materials from beverage compositions by forming adducts. It is thus theorized that our mixtures of low molecular weight aminopolysaccharides derived from chitosan and hydrolyzed keratin protein may penetrate hair fibers, forming adducts with each other and with the keratin protein. This network may then act on cuticle layers to form a more uniform surface manifested in enhanced combing and to provide some rigidity to the cortex manifested as enhanced set holding.
To determine the depth of penetration into hair fibers and to possibly substantiate formation of adducts in the fiber, known staining techniques were employed to show significant staining of the cuticular area of treated fibers along with staining of a portion of the cortical area inside the cuticle. It is our opinion that this evidence, along with the lack of significant surface coating as determined by scanning electronmicroscopy, points strongly to interior adduct formation.
The prior art contains many references to the use of a wide variety of protein materials in hair treating compositions. Among these may be mentioned Canadian Pat. No. 865,694, describing cosmetic compositions for the treatment of hair which contain polypeptides obtained by heating collagen-containing materials in water to produce a hydrolyzate, which is purified by ion exchange and further hydrolyzed with an enzyme material having proteolytic activity. U.S. Pat. No. 3,842,848 describes aqueous hair treating compositions containing a keratin polypeptide hydrolyzate produced by the acid hydrolysis of hair.
A method for treating hair to improve the manageability, body and sheen thereof is disclosed in U.S. Pat. No. 4,186,188. The method involves the application, from aqueous solution, of certain charged polypeptides formed by the hydrolysis of certain proteins. Mixtures of amino acids and vitamins are disclosed in U.S. Pat. No. 4,201,235 for the purpose of enhancing softness and luster and imparting fuller body to the hair.
U.S. Pat. No. 4,275,748 describes a method of modifying filamentous keratins by contact with an aqueous solution containing, among other ingredients, a collagen polypeptide/amino acid composition.
Compositions for providing improved conditioning of the hair by the application of aqueous compositions containing salts of chitosan are disclosed in U.S. Pat. No. 4,202,881 and French Pat. No. 2,354,760.
While the prior art described above shows that both chitosan and a wide variety of protein hydrolyzate materials have been used in the treatment of human hair in the past, none of the references discloses or suggests the employment of the adducts discovered by us as described hereinafter.